This research proposal has been designed to investigate the molecular nature of mammalian spermatogenic cell membranes. Particular emphasis will be placed on the isolation and biochemical characterization of cell surface antigens specific to mouse spermatogenesis. These experiments will utilize isolated populations of spermatogenic cells including: primitive type A spermatogonia, type A spermatogonia, type B spermatogonia, preleptotene spermatocytes, leptotene/zygotene spermatocytes, pachytene spermatocytes, round spermatids, residual bodies, and mature spermatozoa. Purified plasma membranes will be prepared and analyzed. The general objectives of this proposal include: 1) the preparation of plasma membranes from early spermatogenic cells; 2) the electrophoretic comparison of purified membranes at all stages of spermatogenesis; 3) the analysis of membrane lipid composition; 4) the immunological identification of stage-specific spermatogenic cell surface antigens; and 5) the analysis of the in vitro biosynthesis of plasma membrane components by purified spermatogenic cell populations.